Extreme pressure lubricant additive



Unit

res

EXTREME PRESSURE LUBRICANT ADDITIVE No Drawing. Application January 25, 1956 Serial No. 561,350

25 Claims. (Cl. 25248.4)

This invention relates to novel lubricating oil additives and superior lubricant compositions containing the same. More particularly, this invention relates to additives for lubricating oils which lend excellent extreme pressure properties thereto.

This is a continuation-in-part of our application Serial No. 515,788, filed June 15, 1955, now abandoned.

With the continuing development and improvement of industrial engines and other heavily loaded machinery, the need for improved lubricating oils exhibiting superior extreme pressure qualities increases. New turbine engines, for example, have increased gear loads and consequently require oils exhibiting high EP properties.

In addition to the importance of having lubricating oils used in heavy machinery exhibit good EP properties, it is also important that the oils are not oxidized under extreme pressure conditions. Therefore, it is necessary that the EP additive does not have a pro-oxidant effect or destroy the eifect of any anti-oxidant used. Further, the EP additive should be non-corrosive and nonemulsifying.

In accordance with the present invention new halogencontaining condensation products are formed by the reaction of polyhalogenated aliphatic esters with alkali metal or alkaline-earth metal salts of organic mercaptans and the products combined with mineral oil in amounts sufiicient to improve the EP properties of the oil. The new additives of the present invention do not impair the eifect of anti-oxidants .present in the oil nor do they have a pro-oxidant effect on the oil. In addition, these additives are non-corrosive and non-emulsifying. This is unexpected since the usual El agents severely degrade the anti-oxidants present in turbine oils.

Esters of polyhalcgenated aliphatic acids such as chlorinated, brominated, and iodinated aliphatic esters having from 6 to 22 carbon atoms in the acid portion of the molecule are useful. Advantageously, the esters are derived from acids containing from 12 to 20 carbon atoms. The following are specific examples of the esters which are useful in accordance with this invention: Methyl pentachlorostearate, ethyl hexachlorostearate, ethyl trichlorooleate, butyl hexachlorolinoleate, ethyl tribromostearate, butyl tetraiodooleate, methyl pentaiodostearate, propyl pentabromostearate, 2-ethylhexyl trichloropalmitate, 2-ethyldecyl tetrachlorodecanoate, methyl trichlorocaprylate, Z-methylpentyl hexachlorolaurate, ethyl tetrachloromyristate, propyl pentachlororicinoleate, ethyl hexachlorochaulmoograte, methyl trichlorohexanoate and methyl hexachlorobehenate.

It is evident from the above examples that the esters useful in the present invention are formed from polyhalogenated aliphatic acids containing from 6 to 22 carbon atoms and aliphatic alcohols containing from 1 to 12 or more carbon atoms. it is also evident that the acid portion of the esters is pol halogenated which We have found extremely advantageous not only for superior EP properties but also to obtain the advantageous property of non-corrosivity to copper and steel.

atent However, the preferred esters are formed with polyhalogenated longchain aliphatic acid portions having from 4 to 6 substituted halogen atoms and from 12 to 20 carbon atoms, and shortchained alcohol portions having from 1 to 6 carbon atoms. An especially preferred ester is methyl pentachlorostear'ate.

The alkali metal and alkaline-earth metal salts of aliphatic mercaptans which are useful in the present invention include lithium, sodium, potassium, calcium, strontium and barium salts of organic mercaptans containing from 1 to 20 carbon atoms in the molecule. Some examples of the aliphatic mercaptides useful in the present invention are: Sodium methyl mercaptide, sodium t-octyl mercaptide, sodium t-butyl mercaptide, lithium methyl mercaptide, lithium butyl mercaptide, sodium lauryl mercaptide, potassium methyl mercaptide, potassium t-octyl mercaptide, potassium butyl mercaptide, potassium tbutyl mercaptide, potassium lauryl mercaptide, lithium lauryl mercaptide, calcium methyl mercaptide, calcium t-octyl mercaptide, strontium methyl mercaptide, strontium t-octyl mercaptide, barium methyl mercaptide and barium t-octyl mercaptide. The preferred aliphatic mercaptides are the alkali metal and alkaline-earth metal salts of methyl and t-octyl mercaptan on the basis of their excellent performance as EP :agents of the compounds manufactured therewith in accordance with this invention.

Aryl mercaptides are also extremely useful in the invention and examples of these are: The alkali metal and alkaline-earth metal salts of thiophenols and thiocresols. A preferred aryl mercaptide fraction is derived from the mixture of thiophenols and tbiocresols isolated from petroleum acid oil.

The reaction products are formed by reacting from about 1 to 3 moles of a polyhalo-ester with from about 0.5 to 5 moles of metal mercaptide. Advantageously, the new product is formed with a mercaptide concentration less than that required to react with the total halogens on the ester, e.g., the mole concentration of mercaptide is less than stoichiometric.

The preferred general procedure for obtaining the reaction products is as follows: An alkali metal, alkalineearth metal or hydroxide of either, is dissolved in a solvent such as methanol and a mercaptan is added. The poylhalogenated aliphatic ester is dissolved in a solvent such as toluene and added to the metal-mercaptide solution. The mixture is'refluxed with stirring at a temperature above the boiling point of the solventsused, such as above 111 C. the B1. of toluene. The mixture is then cooled, poured into water, acidified and extracted with benzene; The benzene extract is Water-washed, dried and evaporated to C. at 1 mm. to yield the desired product.

The halogen-containing reaction product of a halogenated aliphatic ester and an alkali metal or alkaline earth metal salt of an organic mercaptan in accordance with the present invention is added to a lube oil in amounts ranging from 0.1 to 5% by Weight, however, we prefer from 0.25 to 2%.

The lube oils with which our new reaction product may be used to obtain a superior lube oil composition can be broadly described as hydrocarbon mineral base oils, synthetic lubricating base oils or mixtures thereof.

The hydrocarbon mineral oils can be parafiin base, naphthene base or residual type oils including mixtures of any and all of them.

The synthetic lubricating bases are of the ester or ether type. High molecular weight, high boiling liquid aliphatic dicarboxylic acid esters possess excellent viscositytemperature relationships and lubricating proper-ties'and are finding ever increasing utilization in lube oils and greases adapted for high and low temperature lubrication. Examples of this class of syntheticlubricatin g i 3 bases are the diesters of acids such as sebacic, adipic, azelaic, alkenyl succinic, etc.; specific examples of these diesters are di-Z-ethylhexyl sebacate, di-2-ethylhexyl azelate, di-Z-ethylhexyl adipate, din-amyl sebacate, di-2- ethylhexyl-n-dodecyl succinate, di-2-ethoxyethyl sebacate, di-2'-methoxy-2-ethoxyethyl sebacate (the methyl Carbitol diester), di-2-ethyl-2-n-butoxyethyl sebacate (the 2- ethylbutyl Cellosolve diester), di-Z-n-butoxyethyl azelate (the n-butyl Cellosolve diester) and di-2'-n-butoxy-2-ethoxyethyl-n-octyl succinate (the n-butyl Carbitol diester).

Polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid of the type described above, a glycol and a monofunctional aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid in specified mole ratios are also employed as the synthetic lubricating base in the compositionsof this invention; polyesters of this type are described in US. 2,628,974. Polyesters formed by reaction of a mixture containing specified amounts of dipropylene glycol, sebacic acid and 2-ethylhexanol and of amixture containing adipic acid, diethylene glycol and 2-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

Polyalkylene ethers as illustrated by polyglycols are also used as the lubricating base in the compositions of this invention. Polyethylene glycol, polypropylene glycol, polybutylene glycols and mixed polyethylene-polypropylene glycols are examples of this class of synthetic lubricating bases.

The sulfur analogs of the above-described diesters,

polyesters and polyalkylene ethers are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-2-ethylhexyl thiosebacate and di-n-octyl thioadipate; polyethylene thioglycol is an example of the sulfur analogs of the polyalkylene glycols; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and Z-ethylhexyl mercaptan.

The reaction products of the present invention as pointed out are particularly useful when incorporated in turbine oils. These oils may be broadly characterized as parafiin base and naphthene base oils having a viscosity range from 80 to 780 SSU at 100 F., a flash range of from 320-520 F., a pour range of from +20 to 45 F., and viscosity index of from 95 to less than 10.

Turbine oils usually have anti-oxidants and anti-rust agents incorporated therein to inhibit oxidation and the accompanying rusting which occur particularly under the severe conditions to which turbine oils are subjected. The broad class of anti-oxidants which are preferred in accordance with the present invention are the alkyl-substituted phenols used in amounts ranging from 0.01 to 5.0 percent and preferably from 0.05 to 2.0 weight percent of the lubricant composition. The anti-rust compounds which may also be advantageously admixed with turbine oils are broadly defined as aliphatic-substituted aliphatic dicarboxylic acids used in amounts ranging from 0.005 to 3.0 percent and preferably from 0.005 to 1.0 weight percent of the lubricant composition. These anti-rust compounds can be used with or without minor portions of mono or diesters of inorganic acids or mixtures thereof, such as a mixture of mono and dilauryl phosphoric acid esters. For a further description of these antirust compounds see US. Patent 2,452,319 to John A. Patterson and Herman D. Kluge, issued October 26, 1948, and assigned to The Texas Company.

Other additives such as anti-foam agents can be advantageously incorporated in the turbine oils useful in the present invention and these additives which perform their usual function are silicones such as dimethyl silicone.

Preparation of the products of reaction of various polyhalogenated aliphatic esters with alkali metal salts of organic mercaptans is demonstrated in the following examples.

and extracted with benzene.

4 EXAMPLE I This example involves the preparation of the product of the reaction of the sodium salt of lauryl mercaptan with methyl pentachlorostearate (MPS).

11.9 g. (0.52 gram-atoms) of sodium was dissolved in 1000 ml. of methanol and 104 g. (0.52 mole) of lauryl mercaptan added. 244 g. (0.52 mole) of methyl pentachlorostearate (MPS) dissolved in 200 ml. of toluene was added. The mixture was refluxed for 6 hours with stirring. After cooling the mixture was poured into water, acidified, and extracted with benzene. The extract was water-washed, dried and the solvent evaporated off by utilizing temperatures up to C. at 1 mm. 273 g. of

the desired product, hereafter called lauryl mercaptide- MPS, was obtained. This product has a Neut. No. 0.7 and analyzed 4.93% sulfur and 22.0% chlorine.

EXAMPLE II was obtained which had a Neut. No. of l and analyzed 5.6% sulfur and 7.1% chlorine.

EXAMPLE III This example involves the preparation of the product of the reaction of the sodium salt of butyl mercaptan with methyl pentachlorostearate (MPS) 11.5 g. (0.5 gram-atoms) of metallic sodium was dissolved in 1000 ml. of methanol and 45 g. (0.5 mole) of butyl mercaptan added. 235 g. (0.5 mole) of methyl pentachlorostearate was dissolved in 500 ml. of toluene and added to the above solution. The entire mixture was then refluxed with stirring for 4 hours. After cooling, the mixture was poured into water, acidified and extracted with benzene. The extract was water-washed, dried and the solvent evaporated by the utilization of temperatures up to 150 C. at 1 mm. About 235 g. of the desired product, hereinafter called butyl mercaptide-MPS, was obtained. The product had a Neut. No. of 3.5, and analyzed 5.5% of sulfur and 26.9% of chlorine.

EXAMPLE IV This example involves the preparation of the product of the reaction of sodium salt of t-octyl mercaptan with methyl pentachlorostearate (MPS).

11.5 g. (0.5 gram-atoms) of sodium, 73 g. (0.5 mole) of t-octyl mercaptan and 235 g. (0.5 mole) of methyl pentachlorostearate (MPS) were reacted by the procedure utilized in Example 111. About 237 g. of the desired product, hereinafter called t-octyl mercaptan-MP8, was recovered with a Neut. No. of 7.6 and analyzed 3.37% of sulfur and 28.4% of chlorine.

EXAMPLE V This example involves the preparation of the product of the reaction of the sodium salts of a mixture of thiocresol and thiophenol derived from petroleum thioacid oil with methyl pentachlorostearate (MPS).

472 g. (1 mole) 'of methyl pentachlorostearate was dissolved in 500 ml. of methyl Cellosolve. 40.5 g. (l gram-aton1) of sodium hydroxide was dissolved in 1000 ml. of methyl Cellosolve and 126.5 g. (1.05 moles) of a mixture of thiocresol and thiophenol, derived from petroleum thioacid oil, added thereto. Over a 3 hour period the mercaptide solution was added to the refluxing solution of methyl pentachlorostearate with constant stirring. After cooling, the mixture was poured into water, acidified The extract was waterwashed, dried and the solvent evaporated. 530 g. of the 5. desired product, hereinafter called thioacidoil-MPS; was obtainedl The product was analyzed and'show'ed 'a sulfur content of 5.6%, a chlorine content of 24.2%- and a Neut. No. of 4.-

EXAMPLE VI This example involves the' preparation of theproduct of the reaction of the sodium salt of methyl mercaptan with methyl pentachlorostearate ('MPS).

46 g. (2 gram-atoms) of'so'dium was dissolved in 2 liters of absolute methanol. 72 g. (1.5 moles) of methyl mercaptan was added under the surface. This solution was introduced, over aten-minute period,'into a refluxing (65 C.) solution of 940 g. (2 moles) of MP8 in 500 ml. of absolute methanol. R'efluxing' 'was continued four hours.

The cooled product was divided equally between two separatory funnels, each containing 3 liters of water; 100 ml. of concentrated HCl, 500 ml. of ether, and 500 ml. of methylpentanes. The mixtures were shaken, and the water layers removed and each extracted with oneiliter of 50:50 etherzmethylpentanes. The combined organic layers were washed with 4'-'liter portions of water till neutral to Congo red paper, dried overnight over anhy phoric acid esters, and about 0.001% by weight of'an anti-foam concentrate comprising dimethyl silicone in a 10% kerosene solution.

The above tabulated data are indicative of an extremely improved lube oil with respect to extreme pressure properties' which is readily discernible by one skilled in the art.

T he methyl-mercaptide-MPS product has also been su b' jected' to the Ryder gear scuff test, a well known procedure for testing the anti wear properties of lubricants. The results were very favorable and showed that the base oil-additive blend, already mentioned before Table I, witha 1% addition'of methyl meroaptide-MPS withstood a gear to oth'load'of'2840'lbs. per inch (check 2850) as compared to a tooth load determination of 1410 lbs. per inch for the base oil 'additive blend alone.

The following table shows the superiority of our new product with respect to the important properties required in a turbine oil. The turbine oil used is that base oil described previously as used with the products of Table I and the oxidation and rust inhibitors (0. and R.) and anti-foam agent are the sameas described as incorporated in the base oil used'in'Table I and they are used in the same amounts.

Table II Emulsion, ASTM Oxid. Salt 130 F. Hr. to 2.0 Water Corrosion, Neut. No. Rust CS, 212 F.

Test Min. Unit,

Base oil without 0. and R... Base oil with O. and R 1,100; 1,125.... Pass.... -10 0 Neg.

Wt. percent in Base Additive Oil with O. and R.

t-octyl mereaptide MPS..-.. 900; 1,000 Pass..-.. Neg. butyl mercaptide-MPS 650; 800 Pass.-.. 15 5 Neg. lauryl mercaptide-MP S 825; 875. Pass...- 17 2 Neg. lauryl mercaptide-MDS-..-. 550 Pass.... 14 5 Neg' methyl mercaptide-MPS..-- 1,100; 1,200.... Pass..-. 15 10 Neg drous calcium chloride, and stripped to a maximum temperature of 130 C. (265 F.) first one water pump and finally at 0.3- mm. About 794 g. of the product, hereinafter called methyl mercaptide-MPS,- was obtained. This product had a Neut. No. of 10.0, and analyzed 29.3% of chlorine, 4.94% of sulfur and 0.01% of mercaptan sulfur.

The following table shows the results of tests on the new reaction products with respect to E? and anti-Wear properties in a base oil having a viscosity of 500 SSU at 100 F., a pour of -l0 F. max., a flash of 380 F. min, a Neut. No. 0.1 and an API gravity of 22.5.

The base oil had the following additives incorporated therein: Approximately 0.3% by weight of the antioxidant 4 methyl 2,6-di-t-butylphenol, approximately 0.033% byweight of an-anti-rust concentrateco'rnprising a mixture of 90% of a C propylene tetramer succinic acid and 10% of a mixture of mono and dilauryl phos- The above table demonstrates that the oxidation and rust inhibitors in the base oil are not appreciably degraded by the EP additive reaction products of the present invention. Although there is some slight degradation of their effectiveness, it is greatly overridden by the much better EP properties of the oil whereas the usual EP agents destroy the efiect of oxidation inhibitors, particularly to the extent that the lubricants lose their value as useful turbine oils or the like. The preferred additives, methyl meroaptide-M'PS and t-octyl mercaptide- MPS, have the least degrading effect on the anti-oxidant present in the base oil as adequately shown by the results in the ASTM oxidation test above. Lauryl mercaptide- MP8 is also excellent with respect to both EP properties and effect on oxidation and rust inhibitors.

It is, therefore, seen from the above tables that the reaction products of this invention are excellent EP agents and have no appreciable effect on the oxidation and rust inhibitors present in the base oil.

Obviously, many modifications and variations ofthis invention as above set forth may be made without departing from the spirit and scope thereof, and only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. As a new compound, a halogen-containing product of the reaction of about 1 to 3 moles of a polyhalogenatedaliphatic carboxylic acid ester wherein the acid portion has from 6 to 22 carbon atoms and the alcohol portion has from 1 to 12 carbon atoms with about 0.5 to 5 moles of a metal salt of an organic mercap-tan, said metal being selected from the group consisting of alkali and alkaline-earth metals. I

2. A new compound as-described in. claim 1 wherein said ester has an acid portion of at least 12 carbon atoms and an alcohol portion of from 1 to 6 carbon atoms.

3. A new compound as described in. claim 1 wherein the product is formed with a mercaptan salt concentration less than that required to react with the total halogens on the ester. i

4. As a new compound, a chlorine-containing product of the reaction of from 1 to 3 moles of a polychlorinated aliphatic carboxylic acid ester having an acid portion of from 12 to 22 carbon atoms and an alcohol portion of from 1 to 6 carbon atoms with from 0.5 to moles of an alkali metal salt of an organic mercaptan, said product being formed with a mercaptan salt concentration less than that required to react with the total chlorine atoms on the ester.

5. A new compound as described in claim 4 consisting of the chlorine-containing product of the reaction of methyl pentachlorostearate and the alkalimetal salt of an aliphatic mercaptan..

6. A new compound as described in claim 4 consisting of the chlorine-containing product of the reaction of methyl pentachlorostearate and the alkali metal salt of methyl mercaptan.

7. A new compound as described in claim 4 consisting of a chlorine-containing product of the reaction of methyl pentachlorostearate and an alkali metal salt of t-octyl mercaptan.

i 8. A new compound as described in claim 4 consisting essentially of a chlorine-containing product of the reaction of methyl pentachlorostearate and the alkali metal salt of t-butyl mercaptan.

9. A new compound as described in claim 4 consisting essentially of the chlorine-containing product of the; reaction of methyl pentachlorostearate and the alkali 11. An extreme pressure lubricating oil comprising a mineral lubricating oil and a minor amount of the halogen-containing product of the reaction of about 1 to 3 moles of a polyhalogenated aliphatic carboxylic acid ester wherein the acid portion has from 6 to 22 carbon atoms and the alcohol portion has from 1 to 12 carbon atoms with about 0.5 to 5 moles of a metal salt of an organic mercaptan, said metal selected from the group consisting of alkali and alkaline-earth metals, sufiicient to improve the extreme pressure property of said oil.

12. An extreme pressure lubricating oil as described in claim 11 wherein said ester has an acid portion of at least 12 carbon atoms and an alcohol portion of from 1 to 6 carbon atoms.

13. An extreme pressure lubricating oil as described in claim 11 wherein the product is formed with a mercaptan salt concentration less than that required to react with the halogens on said ester.

14. An extreme pressure lubricating oil as described in claim 11' wherein said minor amount is from 0.1 to 5% by weight.

15. An extreme pressure lubricating oil composition comprising a mineral lubricating oil and from 0.25 to 2% by weight of the chlorine-containing product of the reaction ofaboutlto 3 moles of apolychlorinated aliphatic carboxylicacid ester having-an acid portion of from '12 t .2 ca n at m eudl n. lce o Portion of from 1 to 6 carbon atoms, with about 0.5 to 5 moles of an alkali metal salt of an organic mercaptan.

16. An extreme pressure lubricating oil as described in claim. 15 wherein the ester is methyl pentachlorosma HI V 17. An extreme pressurelubr'icating oil as described in claim 15 wherein the salt is metal aliphatic mercaptide.

18. An extremelpressure lubricating oil as described in claim 15 wherein the salt is alkali metal, methyl mercaptide.

19. An extreme. pressure lubricating oil as described in claim 15 wherein the salt is alkali metal t-octyl mercaptide. 7 m

20. An extreme pressure lubricating oil as described in claim 15 wherein'the' salt is alkali metal t-butyl mercaptide. i

21. An extreme pressure lubricating oil as described in claim 15 wherein the salt is the alkali metal salt of amixture of thiophenols and'thiocresols obtained from petroleum thioacid oil 22. An extreme pressure lubricating oil comprising a mineral lubricating oil and from 0.25 to 2% by weight of the product of the reaction of 1 mole methyl pentachlorostearate with lmole of the alkali metal salt of t-octyl mercaptan.

23. An extreme pressure lubricating oil composition comprising a mineral lubricating base oil, from 0.01 to 5.0 weight percent of an alkyl-substituted phenol, and a halogen-containing reaction product of about 1 to 3 "moles of a polyhalogenated aliphatic carboxylic acid ester having an acid portion of from 6 to 22 carbon atoms and an alcohol portion of from 1 to 12 carbon atoms and about 0.5 to 5 moles of a metal salt of an organic mercaptanin an amount sufiicient to increase the extreme pressure properties of said oil composition, said metal selected-from the group consisting of alkali and alkaline-earth metals.

24. An extreme pressure lubricating oil composition comprising a mineral lubricating base oil, about 0.01 to 5.0% by weight of 4-methyl-2,6-di-t-butyl phenol, about 0.005 to 3.0% by weight of an oil soluble alkenyl succinic acid, and about 0.1 to 5.0% by weight of the reaction product of 1 mole of the alkali metal salt of an aliphatic mercaptan and 1 mole of methyl pentachlorostearate.

25. An extreme pressure lubricating oil composition comprising a mineral lubricating base oil, about 0.05 to 2% by weight of 4-methyl-2,6-di-t-butylphenol, about 0.005 to 1% by weight of a mixture of about alkenyl succinic acid and about 10% of a mixture of mono and dilauryl phosphoric acid esters, and about 0.25 to 2% of the reaction product of 1 mole of the alkali metal salt of t-octyl mercaptanand 1 mole of methyl penta' chlorostearate.

References Cited in thefile of this patent UNITED STATES PATENTS 

11. AN EXTREME PRESSURE LUBRICATING OIL COMPRISING A MINERAL LUBRICATING OIL AND A MINOR AMOUNT OF THE HALOGEN-CONTAINING PRODUCT OF THE REACTION OF ABOUT 1 TO 3 MOLES OF A POLYHALOGENATED ALIPHATIC CARBOXYLIC ACID ESTER WHEREIN THE ACID PORTION HAS FROM 6 TO 22 CARBON ATOMS AND THE ALCOHOL PORTION HAS FROM 1 TO 12 CARBON ATOMS WITH ABOUT 0.5 TO 5 MOLES OF A METAL SALT OF AN ORGANIC MERCAPTAN, SAID METAL SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE-EARTH METALS, SUFFICIENT TO IMPROVE THE EXTREME PRESSURE PROPERTY OF SAID OIL. 